T02_P01

RESEARCH ON MORTAR RADIOCARBON DATING IN FLORENCE: STATE OF THE ART AND FUTURE PERSPECTIVES

Barone S^1,2,  Fedi M¹, Liccioli L¹, Calandra S³, Cantisani E⁴, Salvadori B⁴, Garzonio C⁵

¹INFN - Sezione di Firenze, Sesto Fiorentino (FI), Italy, ²Università degli Studi di Firenze, Department of Physics and Astronomy, Sesto Fiorentino (FI), Italy, ³Università degli Studi di Firenze, Department Of Chemistry "Ugo Schiff", Sesto Fiorentino (Fi), Italy, ⁴ISPC - CNR, Sesto Fiorentino (Fi), Italy, ⁵Università degli Studi di Firenze, Department of Earth Science, Firenze, Italy

As many studies have so far pointed out, despite the easiness of the principle, radiocarbon dating of mortars may present many issues in its application. Such issues are ascribable to the vast heterogeneity of mortars: anthropogenic calcite, which is the carbon fraction to be isolated for dating, is typically mixed with aggregates of several different compositions, even carbonaceous, and of different grain sizes; rest of geogenic calcite, as well as areas of uncomplete carbonation may be present; recrystallization phenomena may alter the original carbon content. The research during these years has highlighted that characterization of the mortar prior to dating is mandatory to identify the most efficient procedure to remove the possible contaminations in our mortar samples.

In the last few years, thanks to the multidisciplinary collaboration between INFN and ISPC-CNR in Florence, a procedure for the selection and treatment of mortars to be dated by radiocarbon was developed. The procedure includes a preliminary in-depth characterization of mortars, by means of different analyses such as XRD and FTIR-ATR, and the extraction of CO₂ from the datable isolated fraction through acidification, thanks to a new set-up that allows us to select different aliquots of CO₂ while the acidification reaction takes place. This set-up is coupled with the graphitization line specifically optimized for microsamples, allowing us to analyze small amounts of mortar calcite or one lump at a time. 

In this poster we describe our procedure, the new experimental set-up installed at our laboratories and the results of the first tests.